1. Field of the Invention
The present invention relates to a method for producing a metal implant and the metal implant produced by the method. More particularly, the present invention relates to a method for processing a surface of a metal implant to prevent adhesion with soft tissues and relates to the metal implant produced by the method.
2. Description of the Related Art
Metal implants are widely used in the medical fields and serve as temporary or permanent substitutes of damaged organs. The implants are rigid and generally in the form of a nail, screw, or plate made of titanium or steel. The metal implants must be bio-compatible to be accepted by the tissues of the bodies without causing any harm to the tissues.
However, a metal implant is fixed in a trauma of a body for a long period of time, such that adhesion is apt to occur between the metal implant and soft tissues surrounding the metal implant during recovery of the trauma, causing trouble in the removal of the metal implant after recovery of the trauma. Taking a bone trauma as an example, the trauma area of a patient is generally fixed by a bone plate or bone nail. After recovery of the trauma area by the growth of osteocytes, a second surgery is required to remove the bone plate or bone nail. During the recovery period, the surrounding soft tissues of the bone are apt to grow on the surface of the bone plate or bone nail and, thus, causing co-adhesion between the soft tissues and the bone plate or bone nail. The soft tissues must be scraped from the surface of the bone plate or bone nail before removing the bone plate or bone nail from the recovered trauma area in the second surgery. The cavities formed after removal of the bone plate or bone nail are difficult to heal in a short period of time, resulting in poor healing effect.
To avoid the adhesion between the metal implant and the surrounding soft tissues, U.S. Patent Publication No. 2009/0124984 A1 entitled “MEDICAL APPLIANCE AND PROCESS AND PROCESS FOR PRODUCING THE APPLIANCE” discloses a process including dipping a material for a medical appliance having a metal surface and an electrode into a solution including a hydrophilic organic compound having a polar group, and fixing the hydrophilic organic compound to the metal surface of the material for a medial appliance in accordance with an electrochemical grafting reaction by applying a voltage between a cathode and an anode using the material for a medial appliance as the cathode and the electrode as the anode. The hydrophilic organic compound can reduce the adverse affect resulting from the contact between the metal appliance and the human tissues.
However, the layer of hydrophilic organic compound formed on the metal surface of the metal appliance after the electrochemical reaction (electrochemical grafting) is often uneven due to unevenness of the metal surface. Furthermore, the non-processed metal surface exhibits an uneven oxidation status. Thus, the number of the oxygen atoms is often insufficient for bonding with the free hydrophilic organic compound moved to the metal surface. The efficiency and quality of the electrochemical grafting are limited, failing to provide the most effective result of electrochemical grafting on the metal surface of the metal appliance.
Furthermore, the hydrophilic organic compound directly formed on the metal surface of the metal appliance can not be reliably bonded to the metal surface, such that the electrochemical grafting result is incomplete after use of the metal appliance in the human body. The desired lubricating (anti-adhesion) effect during use of the metal appliance is significantly and adversely affected. Thus, the quality of the electrochemical grafting of the organic compound is risky.
Thus, a need exists for a novel method for treating a surface of a metal implant to effectively enhance the efficiency and quality of electrochemical grafting of an organic compound on the surface of the metal implant.